A typical ink jet printer has a pen that reciprocates over a printable surface such as a sheet of paper. The includes a print head having an array of numerous orifices through which droplets of may be expelled onto the surface to generate a desired pattern. Some ink jet printers have a replaceable ink supply mounted to a stationary position on the printer, and connected to a reciprocating print head by a conduit. This permits the use of a larger ink supply, and avoids the need to replace the print head each time the supply of ink is depleted. Color ink jet printers generally have a multi-chamber cartridge, or several ink supply cartridges each containing a different color of ink.
Printers with remote ink supplies are normally shipped with the ink supplies and print head removed, or in a "dry" condition. This avoids potential leakage of the ink and shelf life reduction that begins when the tubes are filled with ink. If ink were to remain in the ink conduit for an extended period between manufacturing and first use, air may be absorbed by the ink, and water evaporated, undesirably changing the consistency of the ink outside of normal parameters. In addition, the print head may be protected in special packaging against potential shocks during shipping. When printers are shipped "dry," the ink conduits are empty, except for the presence of ambient air.
When setting up such a printer for its first use, as ink flows from the ink supply to the print head and its on-board reservoir, the air volume within the ink tube is forced into the print head reservoir. If the reservoir is sufficiently large, this can be readily accommodated, but leaves a substantial air volume in the reservoir. Thereafter, ambient pressure or temperature variations, such as caused by changing weather or air travel, can generate pressure changes in the air bubble that undesirably force ink from the orifice. The consequences of such leakage include user inconvenience, printer damage, and impaired printing.
These disadvantages may be avoided or reduced by providing an ink jet printer with a body having a paper path, and a carriage operable to reciprocate across the paper path. The printer body has an ink supply receptacle spaced apart from the carriage, with an ink tube extending between the ink supply receptacle and the carriage. A suction apparatus is connected to the tube and generates a negative pressure in the tube relative to ambient pressure, such that ink may be sucked from the ink supply receptacle to remove at least some of the air from the tube.